# @Time    : 2020/11/27 6:47 下午
# @Author  : baii
# @File    : 380. 常数时间插入、删除和获取随机元素
# @Use     :
from random import choice


class RandomizedSet:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.data = set()
        self.index = list()



    def insert(self, val: int) -> bool:
        """
        Inserts a value to the set. Returns true if the set did not already contain the specified element.
        """
        if val in self.data:
            return False

        self.data.add(val)
        self.index.append(val)
        return True


    def remove(self, val: int) -> bool:
        """
        Removes a value from the set. Returns true if the set contained the specified element.
        """
        if val in self.data:
            self.data.remove(val)
            idx = self.index.index(val)
            self.index[-1], self.index[idx] = self.index[idx], self.index[-1]
            self.index.pop()
            return True
        return False


    def getRandom(self) -> int:
        """
        Get a random element from the set.
        """
        return choice(self.index)



# Your RandomizedSet object will be instantiated and called as such:
# obj = RandomizedSet()
# param_1 = obj.insert(val)
# param_2 = obj.remove(val)
# param_3 = obj.getRandom()